1. Field of the Invention
The invention relates to a new, large-scale industirally employable method for the production of aminocyanoacetamide. Aminocyanoacetamide is an interesting intermediate product for the production of, for example, imidazoles, pyridazines, purines, and pteridines.
2. Brief Description of the Background of the Invention Including Prior Art
Several methods are known for the production of aminocyanoacetamide or, respectively, for the production of aminocyanoacetic esters.
A method for the production of aminocyanoacetic acid ethyl ester from hydroxy-iminocyanoacetic acid ethyl ester is known from the German Patent Application Laid Open DE-OS No. 2,700,733 by way of hydrogenation with Raney nickel. The yields achievable according to the reference amount to about 65%. In addition to the unsatisfactory yield and the low quality of the isolated product, it is a big disadvantage that the catalyst can only be regenerated and recirculated with a relatively large expenditure. Such an expenditure is not justifiable for a large-scale industrial production.
It is known from the publication Logeman et al., Chemistry and Industry (1980), p. 541, that hydroxy-iminocyanoacetic acid ethyl ester can be reacted, with sodium dithionite and in the presence of ethanol as a solvent with a yield of 81% for the raw product, into the aminocyanoacetic acid ethyl ester. The generated sulfate waste as well as the application of fire-hazardous ether is a disadvantage of this method. Such methods and processes are avoided wherever possible in view of the environmental problems associated with the disposal of salt wastes.
Finally, it is known from the publication Taylor et al., Journal of the American Chemical Society, 98, 2301, (1976), that hydroxy-iminocyanoacetic acid benzyl ester can be reacted in the presence of aluminum amalgam and ester as a solvent and, in a second step, with methane sulfonic acid, with a yield of 53%, into the methane sulfonate of the aminocyanoacetic acid benzyl ester. This method can no longer be discussed for a technical application in view of the problems associated with the waste disposal of the mercury catalyst.
The method of Smith et al., Journal of the American Chemical Society 76, 6080, (1954), is associated with the same disadvantages. According to the reference, the starting material is hydroxy-iminocyanoacetamide, which is directly hydrogenated with aluminum amalgam to aminocyanoacetamide, with a yield of 59%.